The Fukuda criteria are used for identifying cases of chronic fatigue syndrome (CFS) for research purposes. They are also known as the CDC 1994 criteria as they were developed in conjunction with the US Centers for Disease Control and Prevention (CDC) in 1994. Although the CDC has now adopted newer criteria, the Fukuda criteria are still widely used by researchers.
Primary symptoms
A patient must have 6 months or longer of persistent or relapsing fatigue that is:
- Unexplained following clinical evaluation*
- New or definite in onset (not lifelong)
- Not as a result of ongoing exertion
- Not substantially alleviated by rest
- Associated with a substantial reduction in occupational, educational, social or personal activities
*Clinical evaluation involves thorough history-taking, physical examination and tests to exclude other causes of chronic fatigue
Additional symptoms
A patient must have 4 or more of the following symptoms, present concurrently for 6 months or longer:
- Post-exertional malaise
- Unrefreshing sleep
- Impaired memory or concentration
- Muscle pain
- Pain in multiple joints
- New headaches
- Tender cervical or axillary lymph nodes
- Sore throat
Detailed diagrams of the Fukuda criteria are available (part 1 and part 2), using extracts from the original paper with the wording retained.
Considerations
First, it is worth noting that the Fukuda criteria refer to CFS rather than Myalgic Encephalomyelitis / Chronic Fatigue Syndrome (ME/CFS). ME/CFS was not a term widely used when the criteria were published.
It must also be noted that the Fukuda criteria do not require post-exertional malaise (PEM) to be present in order to identify CFS. Having fatigue as the primary symptom and under-recognising PEM as a key feature of ME/CFS has been criticised as apt to capture too wide a range of illnesses within its scope. Therefore, comparing the results of a study which uses Fukuda criteria to those using newer criteria that consider PEM a cardinal feature may be challenging.
Lastly, because the Fukuda criteria only require 4 out of 8 additional symptoms to be present, it is possible for two individuals to be classified as having CFS despite having minimal symptom overlap. This may limit the comparability of results across studies.
References
- Fukuda K, et al. The chronic fatigue syndrome: a comprehensive approach to its definition and study. Annals of Internal Medicine, 1994; 121(12):953–9. Available at: doi.org/10.7326/0003-4819-121-12-199412150-00009
- Understanding history of case definitions and criteria. Centers for Disease Control and Prevention, 2022. Available at: cdc.gov/me-cfs/healthcare-providers/case-definitions-criteria.html (accessed: 17 April 2023)
